In recent years, with reduction in the thickness of crystal liquid displays and practical application of organic EL, television sets have become thinner. At the same time, speaker systems for television sets have also become thinner. However, in a low-profile speaker system, the propagation direction of sound within a speaker cabinet is limited by its thinness, and effects of standing waves that occur between the opposing walls in the cabinet are larger than a conventional cuboid cabinet. This causes large peaks and troughs in sound pressure frequency characteristics of a speaker, system.
The speaker system disclosed in Patent Literature 1 is a related art to solve this problem. FIG. 13 is a cross-sectional view of the conventional speaker system disclosed in Patent Literature 1. The speaker system illustrated in FIG. 13 includes a cuboid speaker cabinet 60, a speaker unit 63, first acoustic tubes 64a and 64b, and second acoustic tubes 66a and 66b. 
The speaker cabinet 60 includes a top board 61a, a bottom board 61b, and side boards 62a, 62b, 62c, and 62d. Sound absorbing materials 65a and 65b are provided at the openings of the first acoustic tubs 64a and 64b, respectively. Sound absorbing materials 67a and 67b are provided at the openings of the second acoustic tubs 66a and 66b, respectively.
The operations of a conventional speaker system configured as above will be described. When an electrical signal is inputted into the speaker unit 63 attached to the side board 62b of the speaker cabinet 60, sound is also emitted into the speaker cabinet 60. At this time, standing waves occur between the top board 61a and the bottom board 61b opposed to each other in the longer direction of the speaker cabinet 60. The standing waves occur at a frequency f1 having a wavelength that is equal to a half of the distance between the top board 61a and the bottom board 61b. 
Here, the first acoustic tubes 64a and 64b are provided at the corner parts between the side boards 62a and 62d, and between the side boards 62a and 62b of the speaker cabinet 60, respectively. The first acoustic tubes 64a and 64b with end parts closed are perpendicular to the bottom board 61b, maintain a gap X from the bottom board 61b, and have the absorbing materials 65a and 65b at each opening. In addition, each length of the first acoustic tubes 64a and 64b is equal to one-fourth of the wavelength of standing waves which occur at the frequency f1. The first acoustic tubes 64a and 64b absorb and suppress the standing waves at the frequency f1.
Likewise, standing waves occur at a frequency f2 (twice the frequency f1) having a wavelength that is equal to the distance between the top board 61a and the bottom board 61b. Standing waves at the frequency f2 are suppressed by the second acoustic tubes 66a and 66b which are provided at the corner parts between the side boards 62c and 62b, and between the side boards 62c and 62d of the speaker cabinet 60 respectively, in the same configuration as the acoustic tubes 64a and 64b in the speaker cabinet. In this case, each length of the second acoustic tubes 66a and 66b is half length of the first acoustic tubes 64a and 64b (i.e., one eighth of the wavelength of standing waves at the frequency f1).
As a result, the first acoustic tubes 64a and 64b suppress standing waves having a frequency 2n−1 times the frequency f1. Here, n=1, 2, 3 . . . . In addition, the second acoustic tubes 66a and 66b suppress standing waves having a frequency 2(2n−1) times the frequency f1. This reduces disturbance in sound pressure frequency characteristics due to the standing waves of the speaker cabinet 60.